Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHOD FOR WATER TREATMENT
BACKGROUND OF THE INVENTION
[0001] This application claims priority to and the benefit of U.S. Provisional
Patent
Application 62/833,026, filed April 12, 2019, incorporated herein by reference
in its entirety.
[0002] Embodiments described herein relate to systems and methods for removing
a solute
from a solution. More particularly, the embodiments described herein relate to
systems and
methods for the removal of organisms, minerals, other dissolved solids and/or
contaminants
from water.
[0003] There is a need in the industry to develop a zero liquid discharge
system for removing
solutes from fluid. In particular, concentrated industrial waste brines can be
difficult to
dispose of, requiring costly shipping to a processing center along with the
subsequent
processing in evaporator systems which may also be expensive in terms of
energy usage as
well as economic costs.
[0004] By 2050, global water demand is projected to increase by 55% mainly due
to growing
demands from manufacturing, thermal electricity generation, and domestic use.
While 70%
of the world's fresh water supply is used for agricultural purposes, in
developed countries the
industrial market is the biggest consumer, a trend expanding to other
developing markets. Of
the billions of gallons of industrial water used daily, 69%, while treated for
discharge, is not
reused. The U.S. alone produces over 90 trillion gallons of wastewater each
year that is not
re-used.
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[0005] Water recovery from saline sources, such as seawater; brackish ground
water; reverse
osmosis reject streams; produced water; wastewaters; and industrial process
waters; is
necessary to meet municipal and industrial water needs in many regions.
Desalination
technologies are problematic due to high total dissolved solids (TDS)
concentrated in the
reject stream, extensive logistics and supply chain required, and its negative
environment
impact. The disposal of concentrated brine reject streams from treatment
processes has
significant environmental impact, particularly in arid and inland areas.
Evaporator systems
are the only viable solution to treat and reuse wastewater, especially for the
zero liquid
discharge (ZLD) objective. However, this type of treatment of brine reject
from desalination
systems and industrial processes is particularly energy intensive, very
costly, and technically
challenging.
[0006] Thus the inventors have realized a need for a system that may be used
for water
purification and in particular for ZLD applications. ZLD is becoming an
industry priority as
the water market moves to a more sustainable future; driven mainly by
environmental,
economic, and regulatory pressures. The need for evaporative technologies to
better manage
concentrated wastewater and reduce disposal cost for industry seeking ZLD
treatment is
growing. A system that is able to implement a ZLD process by concentrating
highly
contaminated wastewater streams from current industrial processes without
large capital and
operating expenses and logistics supply chain of current evaporators is
therefore desirable.
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[0007] Thus, a need exists for improved systems and methods for water
purification.
SUMMARY AND OBJECTS OF THE INVENTION
[0008] In an embodiment, a water treatment system includes a blower motor,
configured and
arranged to blow a mixture of air and feed water influent containing
contaminants through the
system, a primary evaporator, including an atomizer configured and arranged to
impart
rotataional velocity and radial velocity to the mixture to atomize it, and a
heat exchanger that
is configured to receive the mixture from the primary evaporator and to act as
both a
secondary evaporator, and to receive the mixture from the primary evaporator,
and is further
configured to act as and a primary condenser.
[0009] In an embodiment, a method of operating a water treatment system of the
preceding
paragraph includes operating the system as described herein.
[0010] In an embodiment, a water treatment system further includes a
concentrate
recirculation circuit configured and arranged to deliver a portion of a
concentrated influent to
a mixing point to be mixed with influent upstream of the primary evaporator.
[0011] In an embodiment, a water treatment system further includes an
injection water circuit
configured and arranged to deliver injection water to airflow downstream of
the blower.
[0012] In an embodiment, the injection water circuit includes one or more heat
exchangers
configured to cool hot injection water prior to delivery to the airflow.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention may be better understood with reference to the drawings:
[0014] FIG.1 is a isometric front view of a water processing system in
accordance with an
embodiment.
[0015] FIG. 2 is a schematic diagram of a water processing system in
accordance with an
embodiment.
[0016] FIG. 3 is a side elevation view of a water processing system in
accordance with an
embodiment.
[0017] FIG. 4 is a partially cut away view of an evaporator in accordance with
an
embodiment.
[0018] FIG. 5 is a cutaway view of an atomizer in accordance with an
embodiment.
[0019] FIG. 6 is a partially cut away view of an atomizer and a cone shaped
interface
between the atomizer and the evaporator.
[0020] FIG. 7 is a schematic diagram of a water processing system in
accordance with an
embodiment.
[0021] FIG. 8 is a schematic diagram of a water processing system in
accordance with an
embodiment.
DETAILED DESCRIPTION
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[0022] A water processing system 10 in accordance with an embodiment is shown
in Fig. 1.
The system includes an air/water separator 12, a pair of product water/air
water separators 14,
a product water tank 16, a hot water bath tank 13, and a pair of evaporators
20.
[0023] As shown in Fig. 2, the cycle is driven by a blower motor 30 which
pushes air and
fluid (which may be in the form of steam in some portions of the circuit) to
be processed into
the evaporators. The fluid to be processed includes material in solution or
entrained that is to
be removed from the fluid for disposal. The solute may include, for example
simple salt
(sodium chloride) or the fluid may be industrial wastewater incorporating any
variety of
solutes that may be considered contaminants. For example, the fluid may
include suspended
solids, dissolved solids, bacteria, heavy metals, fungi, pharmaceuticals,
plastic particles, and
nano materials. In the case of food production such as cheese production,
wastewater may
include large loads of organic waste along with saline loads.
[0024] The blower may be, for example, a centrifugal pump or blower that
produces a flow
of air (e.g., inlet air) having a flow rate of between 30 cubic feet per
minute and 3000 cubic
feet per minute and a pressure of between 3 psi. and 40 psi. In some
embodiments, the
blower can produce a pressurized airflow within a plenum or the like having a
pressure of
approximately 5 p.s.i. at a flow rate of approximately 300 cubic feet per
minute. An
intercooler, not shown, can optionally be included to heat up the air on its
way to the
evaporator. Beneficially, the intercooler, along with waste heat from the
power supply may
also be used to warm water at the feed 28 to the evaporator.
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[0025] The water to be treated is run through an evaporator 32 that includes a
heat exchanger
where the relatively hot air from the blower is cooled by the relatively
cooler water. As
shown in Fig. 2, a counter flow heat exchanger 34 receives contaminated water,
which is
warmed by condensation of clean water vapor which condenses and flows out
through the
clean water outflow.
[0026] The evaporators 20 may be shell and tube heat exchangers as seen in
Fig. 4. The
evaporators 20 act as primary condensers and secondary evaporators. In a shell
and tube heat
exchanger, one fluid flows through the tubes while the other flows on the
shell side of the
tubes. Heat flows through the tube walls, so the material should be one that
is a good
conductor of heat. Additionally, it may be useful to use a material that is
corrosion resistant
and have sufficient strength to maintain pressure differentials between the
zones of the
exchanger and between the shell and the ambient pressure. Metals, including
copper, copper
alloys, stainless steels, aluminum, and nickel alloys may be used, for
example. The use of a
large number of tubes provides a large surface area for heat transfer.
[0027] . As best seen in Fig. 5, the water is injected under pressure by
atomizer 40 which
acts as the primary evaporator to cause it to atomize, prior to entering the
shell and tube heat
exchanger. A conical member 42 (Fig. 6) includes holes 44 that are
substantially aligned
with the openings for the tubes, but are not connected. The fluid inside the
tubes undergoes
evaporation, while the fluid outside is condensing. Because the blower motor
30 is on the
outlet side of the evaporators, it produces vacuum inside the tubes, promoting
evaporation in
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the inner region, while the outside is higher pressure promoting condensation
in the outer
region.
[0028] The conical member 42, seen in Fig. 6, allows the airflow, small water
droplets and
crystalline bodies to flow in a sheet along the surface and acts to avoid
deposition of solids on
the surfaces. This may reduce cleaning and descaling requirements. As will be
appreciated,
it may nevertheless be useful to ensure that the evaporator is configured to
allow easy access
for maintenance, cleaning and descaling. The fluid then flows around the
inside of the
evaporator tubes while condensation forms on the outside of the evaporator
tubes. In an
embodiment, the cone is at a same angle as the primary evaporator.
[0029] The atomizer 40 (which may also be referred to as the "pod") is a
device that is
configured to mix liquid influent water with high velocity rotating air to
atomize the fluid.
One example of a type of atomizer that may be used in conjunction with this
system is
described in U.S. Pat. No. 10,507,402, herein incorporated by reference in its
entirety. In
some embodiments, the influent water is further mixed with recirculated
concentrate water as
will be described in greater detail below.
[0030] The atomizer 40 is shaped such that it imparts an angular velocity and
a radial inward
velocity to the water droplets and is able to saturate the air. In an
embodiment, fins 50 impart
a rotational component to the airflow. The air then flows inward along the
flat slot, imparting
the radial inward velocity. This airflow is under partial vacuum. In an
embodiment, the
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atomizer 40 from time to time has feedwater injected into its input flow path
to clean any
deposited solids. This may be on a schedule or an ad hoc basis in embodiments.
[0031] The output of the atomizer/primary evaporator 40 is predominantly fine
aerosols
entrained in the airflow and the aerosol particulates. The interface device
acts to preserve the
aerosols as they pass down the inside of the tubes. The heat moving through
the walls of the
tubes is heating the air, which lowers the relative humidity, allowing the
aerosols to evaporate
further.
[0032] A conical flow equalizer 45 positioned at the outlet end of the shell
and tube unit acts
to create a toroidal flow path that tends to evenly distribute flow among the
tubes, A plate
separator 46 at the output end of the shell and downstream of the equalizer 45
acts to separate
concentrate/vapor mixture. . In an embodiment, the system is configured to be
a zero liquid
discharge system that outputs precipitated solid waste rather than
concentrated brine as a
waste stream.
[0033] While the term zero liquid discharge is used herein, it should be
understood that in
some implementations, the waste stream may include some amount of liquids.
That is, as the
term is used in the art, it may encompass near-zero liquid discharge or
minimal liquid
discharge, and the solids discharged may include some amount of liquid
moisture. Likewise,
a ZLD process may include, in embodiments, a filter press or centrifuge
process to remove
residual moisture from the precipitated solid waste after processing with the
system.
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[0034] In some embodiments, the water purification system can include a
control system (not
shown) to control the flow of air and or water within certain portions of the
system. For
example, the control system can include a set of components such as pressure
sensors and
adjustable valves to monitor and/or control the flow rate and pressure of air
from the blower.
Similarly, the flow rate, pressure, and/or saturation of the solution entering
or exiting the
atomizer assembly and/or the evaporator assembly can be controlled. In this
manner, the
saturation level of the mixture can be monitored and controlled.
[0035] In an embodiment, water may be injected into the blower output to cool
it and re-
saturate the air before going to the primary condenser/secondary evaporator.
Likewise, the
blower itself produces heat, and that heat can be used as part of the energy
involved in
operating the system by passing the output of the blower through a heat
exchanger
(intercooler, as noted above). This will be described in greater detail below
with reference to
FIGS. 7 and 8.
[0036] FIG. 7 is a schematic of an embodiment similar to the embodiment of
FIG. 2, but with
additional structure illustrated. As noted above, FIG. 2 does not illustrate
the intercooler nor
the fluid loop for the intercooler. FIG. 7 includes this feature along with
some others.
[0037] The water processing system 10' of FIG. 7 includes, similarly to the
previously
described embodiment, a blower motor 30 which pushes air and entrained fluid
(which may
be in the form of steam in some portions of the circuit) to drive the flow
through the system.
In this embodiment, a first heat exchanger 31 is optionally included
downstream of the
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blower motor 30. As noted above, the blower motor may produce excess heat.
This heat is
partially captured in the first heat exchanger 31, reducing the temperature of
the airflow from
the blower. In an embodiment, this process serves to align the temperature of
the feedwater
with that of the airflow so that injecting the feedwater does not alter the
temperature of the
process stream. At the same time, the heat exchanger heats a fluid that can be
pumped to the
second heat exchanger 60 where it can be used to heat vapor that is passing
through the
evaporation/condensation portion of the circuit. A heat exchanger pump 62
moves the heat
transfer fluid through the heat exchangers 31, 60.
[0038] The air and vapor mixture from the heat exchanger 31 passes into the
primary
condenser/secondary evaporator 80, and a portion of the vapor condenses and
passes to the
product water tank 16.
[0039] Influent containing material to be removed is provided from influent
tank 64. It is
pumped through the secondary condenser 34 which acts here as an influent
preheater in this
part of the loop. The fluid then flows to a mixing point 66 where it combines
with
recirculated concentrate pumped by the recirculated concentrate feed pump 68
from the
concentrate tank 70. In the embodiment as shown, the recirculated concentrate
feed pump 68
does not receive concentrate for recirculation directly from the concentrate
tank 70, but rather
first the concentrate passes through a sieve separator 72 in a contaminant
tank 74 that is used
to capture the precipitated contaminants. In an embodiment, the sieve
separator may be
periodically removed and the material collected. In an alternate embodiment,
the sieve may
be a continuously or intermittently moving belt such that clean portions of
the belt are placed
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in the flow and portions having precipitated contaminants are removed from the
flow path for
cleaning/release of the contaminants into a collection reservoir. A portion of
the concentrate
is passed back to the concentrate tank by the feed pump 68, while another
portion is
recirculated through the system after mixing with the influent at the mixing
point 66. An
additional scavenger pump 76 may be included for transferring concentrate from
the
concentrate tank 70 to the contaminant tank 74.
[0040] The reinjection serves to align the feed rate with the evaporation rate
of the system.
In an example, for 90 gal/day of feedwater, 300 gal/day of recirculated
concentrate may be
used. As the device is scaled up, it is expected that the recirculation amount
will not increase
in the same ratio, but rather may tend to stay at a similar rate of
recirculation for a larger rate
of feedwater processing. The amount of recirculation can be altered as
necessary to maintain
the feed rate in view of empirical evaporation rates.
[0041] The influent and recirculated concentrate is then mixed with the
liquid/vapor mixture
from the second heat exchanger at a primary evaporator. As in the preceding
embodiments,
the primary evaporator may be an atomizer 40 that feeds atomized liquid mixed
with air
through the secondary evaporator (inside of the evaporator tubes in the
shelland tube heat
exchanger) and to the concentrate separator 82. The concentrate separator 82
separates
concentrate and passes it to the concentrate tank 70, and passes the vapor and
air back
through the blower 30 to begin the loop again.
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[0042] In this embodiment, sensors Sl..S12 may be included to assist in
controlling and
monitoring operation of the system. The sensors may be configured to monitor
parameters
such as temperature, pressure, and flow rates, for example. In an embodiment,
Si monitors
temperature, pressure, and flow rate at the evaporator input, S2 monitors
temperature and
pressure of the evaporator output, S3 monitors temperature and pressure of the
blower input,
S4 monitors temperature and pressure of the blower output, S5 and S6 monitor
temperature
and pressure of the condenser input and output respectively. S8 and S9 monitor
the
temperature of the first heat exchanger liquid input and output respectively.
S7 monitors
temperature of the vapor output of the second heat exchanger and Si 1 and 512
monitor
temperature of the second heat exchanger liquid input and output respectively.
[0043] Turning now to FIG. 8, a further embodiment 10" is illustrated. In this
embodiment,
influent water is pumped from the influent tank 64 via influent pump 90
through the
secondary condenser 34, which acts as a heat exchanger to warm the influent
with heat from
the vapor flow passing through the condenser side of the secondary condenser
34.
[0044] Optionally, influent preheater 92 may be arranged downstream of the
blower 30. The
influent preheater 92 is a heat exchanger configured to remove heat from the
air/vapor loop
generated in the blower 30 and use that heat to further preheat the influent
flow.
[0045] From the influent preheater 92, the influent is passed to the mixing
point 66 where it
is combined with recirculated concentrate. A recirculated concentrate feed
pump 68 provides
the flow of recirculated concentrate from the concentrate separator 82. The
mixed
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recirculated concentrate and preheated influent is atomized at the
atomizer/primary
evaporator 40. As described above, the atomizer 40 is configured to produce a
helical flow
directed radially inward in the atomizer 40. This flow passes from the
atomizer 40 into the
evaporator/primary condenser 80 on the evaporator side which is the inside of
the tube. This
side, as described above, is maintained at a relatively low temperature and
pressure.
[0046] The action of the evaporator 80 produces water vapor, which is
generally clean and
constitutes the majority of the input water. The remainder of the water
remains as a
concentrated fluid ¨ with a high concentration of contaminants which will
generally be in a
droplet form. The liquid concentrate and vapor are passed to the concentrate
separator 82. In
an embodiment, the separator 82 includes two components, a centrifugal type
separator
component, and a dispersion component, allowing the flows to slow down to
permit the air
and water to separate and the liquid to gather in a sump, where the
concentrate is passed back
via the recirculation pump to the mixing point 66. The concentrate is pumped
from the
concentrate separator 82 to the concentrate tank 70, while the vapor and air
are returned to
the input of the blower 30.
[0047] The vapor and air first optionally pass through the influent preheater
92 to remove
excess heat from the blower motor 30 and then cool water is injected at the
water injection
point 96 to further cool the vapor and air. The injection water is cooled by a
heat exchanger
98 that uses ambient air as a coolant. The injection water, vapor, and air
mixture passes
through an injection water recovery separator 100 which is a centrifugal
separator that
separates water from air, and the now hot injection water may be passed
through a heat
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exchanger 60 before being returned to the water injection point 96 via the
heat exchanger 98.
The other loop of heat exchanger 60 will be discussed further below.
[0048] The remaining vapor and air mixture passes through the primary
condenser portion of
the evaporator/primary condenser 80, then from there to the secondary
condenser 34. At the
primary condenser 80, the majority of the vapor is condensed to liquid. A
remaining portion
is condensed in the secondary condenser 34. The liquid, entrained in the
airflow, passes
through a liquid/vapor separator 102 where the product water is separated from
the airflow.
The airflow proceeds, via the heat exchanger 60 back to the evaporator to
continue through
the loop. Product water is pumped by pump 104 from the product tank 16. The
heat
exchanger 60 uses the airflow through its cool side to cool the injection
water that is passing
through the warm side of the exchanger 60. Simultaneously, the airflow is
heated, lowering
its relative humidity due to whatever amount of vapor remains entrained
therein. Optionally
as shown, some of the product water may be pumped by injection water pump 105
to supply
water for the injection loop where it may be injected at injection point 106.
[0049] The description of the present application has been presented for
purposes of
illustration and description, and is not intended to be exhaustive or limited
to the invention in
the form disclosed. Many modifications and variations will be apparent to
those of ordinary
skill in the art. For example, aspects of each embodiment may be combined with
aspects of
each other embodiment. As one example, the preheater may be used with the
embodiment of
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FIG. 2 as well as the embodiments of FIGS. 7 and 8. Various embodiments of
separators and
heat exchangers may find use in each of the different described embodiments.
The specific
placement of pumps may vary from upstream to downstream of the tanks with
which they
interact. The embodiments were chosen and described in order to best explain
the principles
of the invention, the practical application, and to enable others of ordinary
skill in the art to
understand the invention for various embodiments with various modifications as
are suited to
the particular use contemplated. Unless otherwise specified, the term "about"
should be
understood to mean within 10% of the nominal value.
[0050] While common reference numerals are used to denote commonly named
components,
this should not be taken to mean that those components must be identical. In
practice, they
will be designed in accordance with operational considerations of the various
systems,
including, for example, flow rates, type of influent, concentration of
contaminants, and the
like. So, for example, while each system described includes a primary
condenser/secondary
evaporator, those may, in practice, take somewhat different forms.
[0051] As used in this specification, the term "fluid" may be understood to
refer to a liquid, a
gas, a liquid including solids which may be in solution or entrained, or
combinations thereof
The terms "atomize" and "vaporize" describe the process of reducing a liquid
or solution into
a series of tiny particles, droplets and/or a fine spray. For example, as used
herein, a device or
component configured to atomize a liquid and/or produce and atomized flow of a
liquid can
be any suitable device or component that reduces and/or "breaks" the liquid
into a series of
tiny particles and/or a fine spray.
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[0052] As used in this specification, the singular forms "a," "an" and "the"
include plural
referents unless the context clearly dictates otherwise. Thus, for example,
the term "a
member" is intended to mean a single member or a combination of members, "a
material" is
intended to mean one or more materials, or a combination thereof The term
"substantially"
may be understood to encompass a variation of 10%, for example.
[0053] The descriptions above are intended to be illustrative, not limiting.
Thus, it will be
apparent to one skilled in the art that modifications may be made as described
without
departing from the scope of the claims set out below.
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